GB2166899A

GB2166899A - Liquid crystal display device

Info

Publication number: GB2166899A
Application number: GB08527155A
Authority: GB
Inventors: Kiichirou Kubo; Mikio Kanazaki
Original assignee: Hitachi Ltd
Current assignee: Hitachi Ltd
Priority date: 1984-11-09
Filing date: 1985-11-04
Publication date: 1986-05-14
Also published as: GB8527155D0; DE3539531A1; GB2166899B; US4687300A

Description

1 GB2166899A 1

SPECIFICATION

Liquid crystal display device BACKGROUND OF THE INVENTION

The present invention relates to a liquid crystal display device and more particularly to such a device which facilitates electrical connections between a plurality of integrated cir- cuit chips mounted on the substrate thereof.

In recent years, "Chip on Glass" technology has been studied in order to reduce the size of display devices, increase display content, and improve reliability as described in "Chip on Glass" Technology for Large Scale Automotive Dsiplays", Electronic Displays and Informtion Systems, SP-565, International Congress & Exposition, Detroit, Michigan February 27-March 2, '84. By the chip on glass tech- nology, integrated circuits are bonded in chip form directly on a glass substrate of a liquid crystal display device for example.

As display content increases, there is also inner surface of substrate 1. In order to facilitate the electrical connections between a liquid crystal display area and driving circuits it is desirable to arrange all input conductors 14 of the liquid crystal display area along the edge of only one of the substrates 1 and 2. Conductor 11 is formed on the inner surface of substrate 1 and electrically connected to common electrode 7, conductor 12 is formed on the inner surface of substrate 2 and connected to input conductor 14. Conductors 1 land 12 are electrically connected via conducting paste, for instrance, silver paste 13 disposed between substrates 1 and 2.

The inner surfaces of substrates 1 and 2 which contact liquid crystal 4 are worked into liquid crystal controlling planes 8 and 9 where the liquid crystal molecules in the vicinity of these planes are oriented in a given direction.

Such orientation controlling plans can be Jormed by coating the electrode-carrying side of each substrate with an oblique vacuum evaporateion of film of SiO, or by coating the increased the number of segment electrodes electrode-carrying side of each substrate with and as a result often the number of integrated 90 an organic high- molecular film or a film of an circuits for driving of segment electrodes. A inorganic material and rubbing the coated sur standard car display requires 8 to 10 IC's for face in a given direction with cotton or other driver IC's, a microcomputer, and others. means.

When a plurality of integrated circuit chips are Substrates 1 and 2 secured together by a mounted on one surface of a glass substrate, 95 sealing member 3 are sandwiched between a intersections of electrical wiring are often una- pair of polarizers (not shown). A twisted ne voidable, and multilayer wiring which uses two matic type liquid crystal display device is ex conductor planes separated by a dielectric plained in more detail in U.S. Patent Nos.

layer, or crossover connections have been 3,731,986 and 3,918,796 to J.L. Fergason. In used. With regard to cost alone, the crosso- 100 Fig. 1 the surface of substrate 2 is larger than ver connections are preferred to multilayer that of substrate 1.

wiring which needs printing, deposition by Driving integrated circuit chips 16 and 17 evaporation or sputtering of several layers, for a liquid crystal display area are mounted therefore the crossover connections will be on projecting edge 15. Driving integrated cir- cuit chips 16 is for driving of display positions 6, 621-..., 6. and driving integrated circuit ship 17 is for driving of display pisitions 6, 1, 6-21.._ 62n- External contact terminals 18 are also formed on projecting edge 15 and electrically connected in common to driving integrated circiuit chips 16 and 17.

The common signals such as power supply, data signal, clock signal and address signal (chip select), etc. must be input to the driving integrated circuit chips 16 and 17 through the external contact terminals 18, and therefore the crossover connections are generated in the wirings. This relation is shown in Fig. 2. The substrate 2 mounting the driving intqgrated circuit chips 16 and 17 is usually made of glass and therefore it is difficult from the technical point of view to form the wiring pattern at the rear side of substrate 2 by forming the through hole. Accordingly, the multilayer wiring or crossover connections are usually employed for the intersections of wirings as explained above. Also, from the economical point of view, the crossover connections have been preferred. Fig. 1 shows an example explained below.

Fig. 1 shows an exploded view of an example of twisted nernatic type (TN type) liquid crystal display devices which are among the field-effect type liquid crystal display de- vices. The liquid crystal display device shown 110 in Fig. 1 comprises a first substrate 1 and a second substrate 2 both of which are made of transparent glass or other like material and arranged substantially parallel to each other with a predetermined spacing, for example 5 115 to 15 um, and sealed at the periphery with a sealing member 3 such as frit glass or an organic adhesive, and a nernatic liquid crystal 4 encapsulated therein.

Segment electrodes 5, which are transparent 120 and in the form of segments which can be selectively energized to produce various char acters, for each display position 61, 62,.... I 6n, 6n +, 6n+21..... 62, are formed on the inner surface of substrate 2, individual conductors 125 represented by numeral 10 are provided for each of segment electrodes 5, and electrically connected to input conductors 14.

Common electrode 7 which is common to all segment electrodes 5 is formed on the 2 GB2166899A 2 where the crossover ocnnections are employed for the intersections of wirings.

The wirings between the external contact ternrinals 18 and driving integrated circuit chip 16 are made by the wiring conductors 19 through metal coating formed on the substrate 2. This metal coating preferably comprises a vapor deposition four layer structure of chromium/nickel/copper/chromium. On the other hand, the wirings between external contact terminals 18 and the driving integrated circuit chip 17 are electrically connected to the one ends of crossover conductors 21 formred at the inner surface of substrate 1 by the con- ducting paste, for example, silver paste 20 disposed between the substrates 1 and 2 electrically connected in the course of the wiring conductors 19. These crossover conductors 21 are disposed bridging over the wiring conductors 19 at a different level. The conducting paste 22 is disposed at an area on the inner surface of substrate 2 corresponding to the other ends of the crossover conductors 21. These elements and the driving integrated circuit chip 17 are electrically wire-connected through the wiring conductors made of multila yer metal film 23 (wiring conductors 19 and 23 has the four layer structure of Cu-Ni-Cu-Cr in the same configuration).

However, such structure provides such a disadvantage that the contact resistances among conducting pastes 20 and 22, wiring conductors 19 and 23 and crossover conduc tors 21 do not become sufficiently low and in case a plurality of chips are mounted like the liquid crystal display device for display with a large number of digits or graphic display, blur in display or delay of data transmission timing is generated. Moreover, electrical contact by conducting paste is not stable and such crossover connections are inferior from the point of view of space saving.

SUMMARY OF THE INVENTION

An object of the present invention is to provide a liquid crystal display device free from the blurs in display, delay in timing of data transfer, and malfunction due to the electrical resistance of wiring connected to dividing inte- grated circuit chips mounted on the substrate of the liquid crystal display device.

Another object of the present invention is to provide a compact and highly reliable liquid crystal display device with driving integrated circuits integrated on its substrate.

The above-mentioned objects can be accomplished by the present invention which provides a liquid crystal display device comprising: first and second substrates coated on the inner surfaces thereof with electrodes, at least one of said first and second substrates including an extended portion thereof which projects beyond the edge of the other of said substrates, a sealing member disposed around the periphery enclosing liquid crystal material and sealing between the substrates, input conductors disposed on the inner surface of said extended portion and electrically connected to said electrodes; a plurality of driving integrated circuit chips mounted on the inner surface of said extended portion and electrically connected to said input conductors, including a plurality of pairs of input terminals thereof electrically connected, one input terminal con- stituting each pair is arranged in the reverse order on one side of a reference line with respect the other constituting the pair on the other side of a reference line, metal film conductors formed on the inner surface of said extended portion and connecting said corresponding input terminals of said adjacent chips, a plurality of external contact terminals to an external apparatus, formed on the inner surface of said extended portion and electri- cally connected to input terminals of said chip.

BRIEF DESCRIPTION OF THE DRAWINGS

Fig. 1 is an exploded view of a prior art liquid crystal display device; Fig. 2 is an example of wiring diagram of a liquid crystal display device with a large number of segment electrtodes; Fig. 3 is an exploded view of a first embodiment of the invention; Fig. 4 is a wiring diagram of the embodiment in Fig. 3; Fig. 5 is a schematic diagram of a second embodiment of the inention; Fig. 6 is a schematic diagram of a third embodiment of the invention; Fig. 7 is a schematic diagram of a fourth embodiment of the invention; Fig. 8 is an arrangement of input terminals of an integrated circuit chip in a fifth embodiment of the invention; Fig. 9 is a schematic diagram of a sixth embodiment of the invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Referring now to Figs. 3 to 9 wherein line reference characters designate identical or corresponding parts in Fig. 1, a plurality of liquid crystal driveing LSI chips 24, 25 are soldered on the substrate 2. As shown in Fig. 4, the input terminal 34 of LSI chips 24, 25 are arranged in the sequence of B, C,, D, E, F, G, at the right side of the center input termi- nal A and in the reverse order as G2, F2, E2, D,, C2, B2 in the left side of the input terminal A. Moreover, the terminals B, and B2, C, and C2, D, and D2, E, and E2, F, and F,, G, and G2 which form pairs corresponding in both sides of the reference line R-R passing the input temrinal A are internally connected as indicated by a dotted line within the chip and these pairs are also connected to the driving circuit formed within the chip. Therefore, the input signal to the driving LSI chip 24 is input to the driving circuit (not shown) formed on the LSI chip 24 through the wiring 26 formed by a multilayer metal film and terminals A, 13, C2, D2, E2, F,, G, of the LSI chip 24 from the external contact terminals 18A, 1813, 18C, 3 GB2166899A 3 18D and 18E.. Menwhile the input signal to the driving LSI chip 25 is input to the driving circuit (not shown) formed on the LSI chip 25 through the wiring 26, terminals A, B2, C2, D21 5 E2, F2, G, of LS1 chip 24, terminals A, B, C, ID, E, F, G, of the LSI chip 24, wiring 27 formed by the multilayer metal film and the terminals A, B2, C2, D2, E2, F2, G2 of driving LSI chip 25 from the external contact termi- nals 18A, 1813, 18C, 18D, 18E and 18G. The chips and multilayer metal film are connected by wire bond or slodewr bump, but the present invention can be adapted to any type of connecting system.

As explained above, in the present invention, since input wirings of a plurality of LS1 chips 24 and 25 are carried out without using the conducting paste which raises wiring resistance, the input wiring resistance of LSI chips 24, 25 can be kept sufficiently low and reliability can be enahanced easily. This embodiment also provides significant effect for reducing the external size of a display apparatus and has saved the space as compared with the crossover system by about 15%.

In above embodiment, the terminals A, B, B2, Cl, C2, ID, D2, E, E2, F, F2, G, G2 of LS1 chip are all arranged onIV at the one side of chip, but it is also possible to arrange them to a plurality of sides of the LSI chips 28, 29 as shown in the second embodiment of Fig. 5.

In above first and second embodiments, two LSI chips are connected, but it is certainly possible to connect the inputs of the LSI chips even when three or more LSI chips are connected.

Moreover, in above embodiment, the static drive method is employed for commonly drive the segment electrodes 5 with the common electrode 7 but in the third emodiment shown in Fig. 6, the matrix display device, wherein the segment electrodes 30 and scanning electrodes 31 are formed by the striped eleerodes, is employed and a plurality of LSI chips are used for multiplexed driving of the scanning electrodes. The method of driving liquid crystal matrix display device is described in U. S. Patent No. 3,976,362 to Kawakami. The scanning electrodes X, X21. - -, X,, are driven by the LSI chip 32, while the scanning electrodes X,, X,,,.... X16 by the LS1 chip 33. The arrangement of A, B, 13, Cl, C, ID, ID, E, E, F, F, G, G2 of input terminals 34 of LS1 chips 32, 33 is the same as that of the LS1 chips 24, 25.

As is apparent from above description, according to the present invention, each input terminal of LSI chip is formed as pair, a plurality of LSI chips are adjacently arranged on the one plane by reversely arranging the inpt terminals at the one side regarding the certain reference line and the input terminals at the other side and the corresponding input terminais of adjacent LSI chips are wired and thereby crossover wirings of input wires can be eliminated even in case a plurality of signals are input in common to the input terminals of plurality of LS1 chips. Said reference line R-R is not required to pass on the input terminals of LSI chip described in above embodiment and it may be set between the terminals A, A, of the LSI chips 35, 26 as shown in the fourth embodiment of Fig. 7.

As in the case of the fifth embodiment shown in Fig. 8, each pair of the terminals B, and B,, C, and C2, D, and D2, E, and E, F, and F2, G, and G2 of the LSI chip may be arranged asymmetrically to the reference line R-R.

In above embodiments, all of the input terminals 34 of LS1 chip are electrically connected to the driving circuit formed on the chip. However, as in the case of the sixth embodiment shown in Fig. 8, the signals inputted to the LS1 chip 37 and the signals inputted to the LS1 chip 38 are not all in common and these may partly different in some cases where the segment electrodes 30 is driven by the LSI chip 37, while the scanning electrodes 31 by the LS1 chip 38. In this case, it is enough to excessively provide the pairs of internally connected input terminals as in the case of above embodiment, although not connected to the driving circuit formed on the LSI chip.

The pair of B, and B2 among the input ter minals 34 of LSI chips 37, 38 shown in Fig. 9 is not electrically connected to the driving circuit (not shown) formed on the LSI chip.

The signal which is common to both LSI chips is input to A, ID, D2, E, E2, F, F2, G, G2 of the input ternrinals 24 of the LSI chips 37, 38. In case it is required to input different signals for both LSI's, an signal is directly in- put to the terminals C, C2 of the LSI chip 38 from the external contact terminal 18C and the different signal is input to the terminals C, C2 of LSI chip 37 through the exernal contact terminals 18B and the terminals B2, B, of LSI chip 38.

As described above, since a part of the input terminals is provided as the exclusive terminal for wirrings, diferent signals can be applied to the corresponding signal termianis of two LS1 elements without crossover wiring at the single plane. Thereby, the wirings of LSI's for driving which are different in the clock signal, time multiplexing and bias voltage such as the scanning electride driving LSI chip and the segment electride driving LSI chip of the liquid crystal display apparatus can be realized easily, and accordingly the wiring pattern design period in the liquid crystal display apparatus can be curtailed and the process can also be simplified due to eliemination of crossover portions of wirings.

Claims

1. A liquid crystal display device compris- ing: first and second subtrates coated on the 4 GB2166899A 4 inner surfaces thereof with electrodes, at least one of sai&first and second substrates including an extended portion thereof which projects beyond the edge of the other of said substrates, a sealing member disposed around a periphery enclosing liquid crystal material to sea] it between the substrates, input conductors disposed on the inner surface of said ex- tended portion and electrically connected to said electrodes, a plurality of driving integrated circuit chips mounted on the inner surface of said extended portion and electrically connected to said input conductors, including a plurality of pairs of electrically connected, input terminals thereof, one input terminal of each pair being arranged in the reverse order on one side of a reference line with respect to the other input terminal constituting the pair on the other side of the reference line, metal film conductors formed on the inner surface of said extended portion and connecting said corresponding input terminals of said adjacent chips, and a plurality of external contact termi- nals to an external apparatus formed on the inner surface of said extended portion and electrically connected to input terminals of said chip.

2. A liquid crystal display device according to claim 1, wherein the driving integrated circuit chips include a plurality of integrated circuit chips for driving segment electrodes.

3. A liquid crystal display device according to claim 1, wherein the driving integrated cir- cuit chips include a plurality of integrated circuit chips for driving scanning electrodes.

4. A liquid crystal display device according to claim 1, 2 or 3, wherein said input terminals are arranged along a plurality of edges of said driving integrated circuit chips.

5. A liquid crystal display device according to any preceding claim, wherein some of said pairs of input terminals are not electrically connected to driving integrated circuits formed on the chips on which the pairs of input terminals are formed, and are used for electrical connections for other adjacent chips.

6. A liquid rystal display device constructed and arranged to operate substantially as herein described with reference to and as illustrated in Figs. 3 to 9 of the accompanying drawings.

Printed in the United Kingdom for Her Majesty's Stationery Office, Dd 8818935, 1986, 4235. Published at The Patent Office, 25 Southampton Buildings, London. WC2A 'I AY, from which copies may be obtained.